Inhibiting corrosion with nitrogenheterocyclic phosphonic acids

ABSTRACT

&gt;N-((R&#39;&#39;-)NH0-1)0-2-(C(-X)(-Y)-P(=O)(-O-M)N)1-   WHERE   -C(-X)(-Y)-P(=O)(-O-M)2   REPRESENTS A HETEROCYCLIC RING HAVING A NITROGEN ATOM ON THE RING; R&#39;&#39;NH0-1 REPRESENTS AN AMINO-TERMINATED SIDE CHAIN ATTACHED DIRECTLY TO THE RING NITROGEN (WHICH SIDE CHAIN MAY OR MAY NOT BE PRESENT); AND -C(-X)(-Y)-P(=O)(-O-M)2 REPRESENTS A METHYL (OR SUBSTITUTED METHYL) PHOSPHONIC ACID GROUP WHERE M IS HYDROGEN, AN ALCOHOL OR A SALT MOIETY, AND X AND Y ARE HYDROGEN OR A SUBSTITUTED GROUP SUCH AS ALKYL, ARYL, ETC., OF WHICH ONE OR TWO UNITS MAY BE PRESENT DEPENDING ON THE AVAILABLE NITROGEN BONDED HYDROGENS. PROCESS OF INHIBITING CORROSION OF METALS, MOST PARTICULARLY IRON, STEEL AND FERROUS ALLOYS, IN A CORROSIVE MEDIUM, SUCH AS, FOR EXAMPLE, A CORROSIVE OIL-CONTAINING MEDIUM, BY CONTACTING THE SURFACE OF THE METAL, PRIOR TO CONTACT WITH THE MEDIUM OR BY DISSOLUTION IN A SOLVENT AND ADDITI DIUM OR DISSOLUTION IN A SOLVENT AND ADDITION OF SAID SOLUTION TO THE MEDIUM, WITH NITROGEN-HETEROCYCLIC PHOSPHONIC ACIDS AND DERIVATIVES THEREOF CHARACTERIZED BY AMINOMETHYL (OR SUBSTITUTED METHYL) PHOSPHONIC ACIDS OR DERIVATIVES THEREOF BONDED DIRECTLY OR INDIRECTLY, I.E., THROUGH A N-SIDE CHAIN TO THE NITROGEN ATOM IN THE HETEROCYCLIC RING, FOR THE EXAMPLE THOSE CONTAINING IN THE MOLECULE AT LEAST ONE OF THE FOLLOWING UNITS:

United States Patent 3,720,498 INHIBITING CORROSION WITH NITROGEN-HETEROCYCLIC PHOSPHONIC ACIDS Derek Redmore, Ballwin, Mo., assignor toPetrolite Corporation, Wilmington, Del. No Drawing. Original applicationOct. 17, 1968, Ser. No. 768,509, now Patent No. 3,674,804, dated July 4,1972. Divided and this application Aug. 26, 1971, Ser.

Int. Cl. C23f 11/16 U.S. e1. 21--2.s 14 Claims ABSTRACT OF THEDISCLOSURE Process of inhibiting corrosion of metals, most particularlyiron, steel and ferrous alloys, in a corrosive medium, such as, forexample, a corrosive oil-containing medium, by contacting the surface ofthe metal, prior to contact with the medium or bydissolution in themedium or dissolution in a solvent and addition of said solution to themedium, with nitrogen-heterocyclic phosphonic acids and derivativesthereof characterized by aminornethyl (or substituted methyl) phosphonicacids or derivatives thereof bonded directly or indirectly, i.e.,through a N-side chain to the nitrogen atom in the heterocyclic ring,for example those containing in the molecule at least one of thefollowing units:

represents a heterocyclic ring having a nitrogen atom on the ring; R'NHrepresents an amino-terminated side chain attached directly to the ringnitrogen (which side chain may or may not be present); and

where represents a methyl (or substituted methyl) phosphonic acid groupwhere M is hydrogen, an alcohol or a salt moiety, and X and Y arehydrogen or a substituted group such as alkyl, aryl, etc., of which oneor two units may be present depending on the available nitrogen bondedhydrogens.

represents a heterocyclic ring having a nitrogen atom in the ring, R'NHrepresents an amino terminated where 3,720,498 Patented Mar. 13, 1973ice side chain attached directly to the ring nitrogen (which side chainmay or may not be present), and

is a methyl (or substituted methyl) phosphonic acid group where M ishydrogen, an alcohol or a salt moiety, X and Y are hydrogen or asubstituted group such as alkyl, aryl, etc., of which one or two unitsmay be present depending on the available nitrogen bonded hydrogens; andto uses for these compounds, for example, as scale inhibitors, corrosioninhibitors, etc.

Any heterocyclic nitrogen compound having a reactive hydrogen groupattached directly or indirectly, i.e. through an N-side chain to thering nitrogen, which is capable of reacting with a carbonyl compound andthe phosphonic acid or equivalent to yield the products of thisinvention may be employed. Representative examples of heterocyclicnitrogen type systems are as follows:

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HN NCHrI (OH)2 0 (HOhi omN Norm (0H2) w 1116 N ornornNHorni (OEDH H(HO)1P omN Any of the above formulae where the ring is X I X l CNH 3:0(ROME-H gv-b-P-wmi 1120 Where the cyclic amine has two NH groups, thereaction may be The above equation illustrates a cyclic amine whereinthe NH groups are part of the ring structure itself. Also includedwithin the scope of this invention are cyclic compounds where thereactive nitrogen group is on a N- substituted side chain, for example,

in which case corresponding reactions take place with the NH group ofthe side chain, for example,

In the above equation X and Y are hydrogen or a substituted group suchas an alkyl or aryl group, etc., R is an alkyl, aryl, etc. group, and Ris a substituted group, for example alkylene, arylene, oxyalkylene,polyoxyalkylene, polyalkylene amino, etc.

Phosphonic esters are converted to phosphonic acids I or salts thereofaccording to the following reaction X if and/or and other correspondingreactions.

Salts of these can also be prepared, for example salts containing metal,ammonium, amine, etc. groups such as sodium, potassium, triethanolamine,diethanolamine.

A second method comprises reacting (1) a cyclic amine (2) a carbonylcompound such as aldehyde or a ketone and (3) phosphorous acidpreferably in presence of a strong mineral acid such as hydrochloricacid. This method yields the aminomethyl phosphonic acids directly.

These may be illustrated by the following reactions:

The following examples are presented for purpose of illustration and notof limitation.

EXAMPLES Example 1 To a stirred mixture of 2-heptyl-2-imidazoline (45.5g.; 0.25 mole) and diethyl phosphite (34.5 g.; 0.25 mole) was added a40% aqueous formaldehyde solution (19 mls.; 0.25 'mole) during 15minutes. The reaction was rapid and exothermic giving a reactiontemperature of The mixture was stirred for 1 hour following theaddition. Hydrolysis of the resulting phosphonate ester was carried outby heating the ester with 18% hydrochloric acid (200 ml.) for 6 hours.Evaporation of the aqueous acid under vacuum yielded the phosphonic acidwhose structure is represented below Example 2 2-heptyl-2-imidazoline(62 g.; 0.33 mole) was dissolved in a mixture of hydrochloric acid ml.),phosphorous acid (28 g.; 0.33 mole) and water (100 ml.). This solutionwas heated and stirred under gentle reflux while 40% aqueousformaldehyde solution (25 mls.; 0.33 mole) was added during 45 minutes.Heating was continued for 1 hour and the volatiles were removed undervacuum. The residue was the imidazoline phosphonic identical with thatof Example 1.

Example 3 1-(2'-aminoethyl)-2-heptadecyl-2-imidazoline (88.8 g.; 0.25mole) was heated under reflux with phosphorous acid (21 g.; 0.25 mole)and hydrochloric acid (50 ml.) in water (100 ml.). To this stirredmixture was added 40% aqueous formaldehyde (20 ml.; 0.25 mole) during 1hour- Heating was continued t r a fur he 1 ho r before the aqueous acidwas removed under vacuum. The resulting water soluble phosphonic acid isrepresented by the following structure:

Example 4 Using the procedure of Example 3, the same imidazoline (0.25mole) was reacted with phosphorous acid (0.5 mole) and formaldehyde (0.5mole) in the presence of hydrochloric acid (100 ml.) and water (1001111.). The product can be represented by the following formula:

Example 5 N-(Z-aminoethyl) piperazine (32.3 g.; 0.25 mole) was stirredand heated under reflux with phosphorous acid (20.5 g.; 0.25 mole) andhydrochloric acid (50 ml.) in water (50 ml.). During 30 mins. a 40%aqueous solution of formaldehyde (20 ml.; 0.25 mole) was added to abovesolution. After heating for an additional period of 1 /2 hours, theaqueous acids were removed under vacuum to yield an aminomethylphosphonic acid. The product consists mainly of the acid represented bythe following formula:

CHz-CHz 0 EN N-CHzCHzNHCHziKOH):

CH2CHs Example 6 Using the procedure of Example 5, N-(Z-a'minoethyl)piperazine (0.25 mole) was reacted with phosphorous acid (0.5 mole) andformaldehyde (0.5 mole) in presence of hydrochloric acid. The productconsists of a mixture of acids whose main components are represented bythe following formulae:

Example 7 Following the procedure of Example 6 N-(aminoethyl) piperazine(0.25 mole) was reacted with phosphorous acid (0.75 mole) andformaldehyde (0.75 mole) in presence of hydrochloric acid. The productis a triphosphonic acid represented by the formula:

Example 8 N-(Z-aminoethyl) morpholine (32.5; 0.25 mole) was heated andstirred under reflux with phosphorous acid (20.5 g.; 0.25 mole) andhydrochloric acid (50 ml.) in water (50 ml.). To this solution 40%aqueous formaldehyde (20 ml.; 0.25 mole) was added during 45 minutes.Heating was continued for 1 hour before aqueous acid was removed undervacuum. The resulting product was the methyl phosphonic acid representedbelow:

Example 9 N-(Z-aminoethyl) morpholine (32.5 g.; 0.25 mole) was heatedand stirred under reflux with phosphorous acid (20.5 g.; 0.25 mole) andhydrochloric acid (60 ml.) in water (60 ml.). To this solution was addedacetone (15 g.; 0.25 mole) during 1 hour and the heating was continuedfor a further 3 hours. Evaporation of the solvent under vacuum yieldedthe crude phosphonic acid represented by the following formula:

Example 10 This examples illustrates the use of crude amine mixtures inthe preparation of aminomethyl phosphonic acids. Amine A.L-l (JeffersonChemical Co.) (60 g.), [which consists of a mixture of N-(Z-aminoethyl)piperazine (40%), N-(2-hydroxyethyl)piperazine (10-15%) and higheramines] was reacted in the manner of previous examples with phosphorousacid 82 g.; 1 mole) and 40% formaldehyde (75 ml.; 1 mole) in presence ofhydrochloric acid (200 ml.) and water (200 ml.). Evaporation of thesolvents in vacuum yielded a phosphonic acid mixture containing as majorcomponents the following acids:

CYCLIC AM'IDINES The expression cyclic amidine is employed in its usualsense to indicate ring compounds in which there are present either 5 or6 members, and having 2 nitrogen atoms separated by a single carbon atomsupplemented by either two additional carbon atoms or three additionalcarbon atoms in the main chain completing the ring. All the carbon atomsmay be substituted. The nitrogen atom of the ring, involving monovalentlinkages (the 1-position) may be unsubstituted or substituted forexample, an alkylene amine group, a polyalkylene amino group, etc.

These cyclic amidines are further characterized as being substitutedimidazolines and tetrahydropyrimidines in which the two-position carbonof the ring is generally bonded to a hydrocarbon radical or comparableradical derived from an acid, such as a low molal fatty acid, a highmolal fatty acid, or comparable acids, aromatic acids, polycarboxyacids, acids containing heterocyclic rings, and the like.

For details of the preparation of irnidazolines from amines, see thefollowing U.S. patents, U.S. No. 1,999,989 dated Apr. 30, 1935, MaxBockmuhl et al.; U.S. No. 2,155,877 dated Apr. 25', 1939, EdmundWaldmann et al.; and U.S. No. 2,155,878 dated Apr. 25, 1939, EdmundWaldman et al. Also see Chem. Rev. 32, 47 (43), Chem. Rev. 54, 593 (54),and Imidazole and Derivatives, I by K. Hofmann (1953).

Equally suitable for use in preparing compounds useful in this inventionand for the preparation of tetrahydropyrimidines substituted in the2-position are the corresponding polyamines containing at least oneprimary amino group separated from the first primary amino group bythree carbon atoms instead of being separated by only 2 carbons as withimidazolines. This reaction, as in the case of the imidazolines, isgenerally carried out by heating the reactants to a temperature at which2 moles of water are evolved and ring closure is effected. For details 7of the preparation of tetrahydropyrimidines, see German Pat. No. 700,371dated Dec. 18, 1940, to Edmund Waldmann and August Chwala; German Pat.No. 701,322 dated Jan. 14, 1941, to Karl Kiescher, Ernst 'Urech andWilli Klarer, and U.S. Pat. No. 2,194,419 dated Mar. 19, 1940, to AugustChwala.

Substituted imidazolines and tetrahydropyrimidines are obtained from avariety of acids beginning with the one-carbon acid (formic) through andincluding higher fatty acids or the equivalent having 1-30 or morecarbon atoms such as from 8-22 carbons. Modified fatty acids also can beemployed as, for example, phenyl stearic acid or the like. Cyclic acidsmay be employed, including naphthenic acids. A variety of other acids,including benzoic acid, etc., from which the C of the residue is part ofthe ring. The fatty acids employed, for example, may be saturated orunsaturated. Branched long chain fatty acids may be employed. See J. Am.Chem. Soc. 74, 2523 (1952). This applies also to the lower molecularweight acids as well.

More specifically, the nitrogen phosphonic acids are of the formulawhere x is zero or 1, y is 1 or 2 and z is zero or 1 with the provisosthat (1) y is 1 when z is zero and (2) x is 1 and y is 1 when z is 1 and(3) x is zero when v is 2 and z is 1.

As is well known, cyclic amidines containing the 1-position asubstituted group can be prepared by reacting a suitable amine with thedesired carboxylic acid under suitable conditions so as to remove 2moles of water for each equivalent of carboxylate radical. Thus, whereone employs a diamine such as ethylene or propylene diamine, a cyclicamidine which is unsubstituted in the l-position is obtained.

Alternatively amino and polyamino substituted cyclic amidine compoundscan be prepared from polyamines such as a triamine or higher amines, forexample, diethylene triamine, triethylene tetramine, tetraethylenepentamine, corresponding propylene analogues, etc. Thus, when one reactsdiethylene triamine with a carboxylic acid or its esters, one obtainsand with triethylene tetramine one obtains It should be noted that Z canalso be part of an aromatic ring. Thus, by reacting NH: N112 with acarboxylic acid one obtains Thus, cyclic amidines within the scope ofthis invention comprise compounds of the formulae:

R-O 0 Bin-s where RC: and =CRC= are the residues derived from thecarboxylic acid, monocarboxylic acids in ('l) and (3), and dicarboxylicacids in (2), where R comprises a hydrocarbon radical having, forexample, 1-30 carbon atoms, hydrocarbons in which the carbon atom chainis interrupted by oxygen, etc.; and B is a hydrogen or a hydrocarbonradical; D is hydrogen or a radical, for example (AX),,H where X isamino, A is an al'kylene radical containing, for example, 2-3 carbons inits main chain wherein n and x are numbers, for example, 1-10 or higher,advantageously 1-3, but preferably 1, and (CB is, for example, adivalent radical of the formula:

H3 CH3 (5H3 JHa In (2) CB s and the l-substituted side chain may be thesame or different.

Actually, substituted cyclic amidines can be obtained from a variety ofpolyamines. From a practical standpoint, however, the most readilyavailable polyamines are ethylene diamine, diethylene triamine,triethylene tetramine, and tetraethylene pentamine. However, otherpolyamines having some other divalent radical, such as CH3 H l C C H Hcan be employed.

The following table is limited to derivatives of the four most readilyavailable polyamines above indicated.

16a-. p-tert-Butyl-benzoic. CH2CH2NHCH2CH2NH 17a p-Methoxy benzoic.CHzCHzNHCHzCHzNH 18a Toluic CHzCHzNHCHzCHzNH 19a NaphthenicCHzCH2NHCH2CH2NHCH2CH2NH3 243,. Steanc CHzCHgNHCHzCHzNHCHzCHzNHz 259.-.Phenylstearie- CHzOHzNHCHzCHzNHCHzCHzNHg 26a CresotlnicCHzCHzNHCHzCHzNHCHzCHzNH:

apricheterocyclic atom in the ring, where N is present with otherheterocyclic atoms such as oxygen, sulfur, etc., where more than onenitrogen and/ or more than one other heterocyclic atom is present, wherethe heterocyclic system containing one ring or more than one ring, wherethe ring nitrogen is reacted or where the side chain nitrogen or bothare reacted, etc.

Thus

indicates compounds having one or more rings with one or more nitrogenatoms in the ring which rings may contain one or more nitrogen atom inat least one or more of the rights but not necessarily in all the rings,i.e. some of the rings may contain only carbon and hydrogen and/or otherheterocyclic atoms.

As is quite evident, other heterocyclic amines, carbonyls andphosphorous derivatives can be employed herein to yield products usefulin this invention. It is, therefore, not only impossible to attempt acomprehensive catalogue of such compositions, but to attempt to describethe invention in its broader aspects in terms of specific chemical namesof reactants would be too voluminous and unnecessary since one skilledin the art could by following the description of the invention hereinselect proper reagents. This invention lies in the use of suitableheterocyclic amines, carbonyl, and phosphorous derivatives which can beused to form the heterocyclic amino methyl phosphonic acids andderivatives thereof of this invention. To precisely define each specificuseful reactant in light of the present disclosure would merely call forchemical knowledge within the skill of the art in a manner analogous toa mechanical engineer who prescribes in the construction of a machinethe proper materials and the proper dimensions thereof. From thedescription in this specification and with the knowledge of a chemist,one will know or deduce with confidence the applicability of specificreactants suitable in this invention by applying them in the process setforth herein to form phosphonic acid derivatives. In analogy to the caseof a machine, wherein the use of certain materials of construction ordimensions of parts would lead to no practical useful result, variousmaterials will be rejected as inapplicable where others would beoperative. One can obviously assume that no one will wish to use auseless amine or a useless phosphorous derivative nor will be misledbecause it is possible to misapply the teachings of the presentdisclosure to do so. Thus, any heterocyclic amine, carbonyl andphosphorous derivative that can react to form r heterocyclic aminomethylphosphonic acid and derivatives thereof can be employed.

USE AS SCALE INHIBITORS This phase of the invention relates to methodsof inhibiting scale formation and/or the formation of solidscale-forming salts in water or brine comprising adding to said water orbrine small amounts of cyclic amino phosphonate compounds of thisinvention.

Most commercial water contains alkaline earth metal cations, such ascalcium, barium, magnesium, etc., and several anions such asbicarbonate, carbonate, sulfate, oxalate phosphate, silicate, fluoride,etc. When combinations of these anions and cations are present inconcentrations which exceed the solubility of their reaction products,precipitates form until these product solubility concentrations are nolonger exceeded. For example, when the concentrations of calcium ion andcarbonate ion exceed the solubility of the calcium carbonate reactionproduct, a solid phase of calcium carbonate will form.

Solubility product concentrations are exceeded for various reasons, suchas evaporation of the water phase, change in pH, pressure ortemperature, and the introduction of additional ions which forminsoluble compounds with the ions already present in the solution.

As these reaction products precipitate on the surfaces of the watercarrying system, they form scale. The scale prevents effective heattransfer, interferes with fluid flow, facilitates corrosive processes,and harbors bacteria. This scale is an expensive problem in manyindustrial water systems, causing delays and shutdowns for cleaning andremoval.

I have now discovered that the use of the cyclic aminomethylphosphonates of this invention inhibits the formation of scale.

The cyclic aminomethyl phosphonates of this invention Were also found toexhibit good defiocculating or dispersing properties and goodsurfactancy properties. It is highly unusual for both of theseproperties to be effectively exhibited by the same compound. As can beappreciated, such compounds can advantageously be utilized inapplications which can use the foregoing properties, such as, detergentcompositions. In many detergent applications such as textile washing andhard surface cleaning, the ability of the detergent composition toremove the soil and keep the soil suspended in the washing medium is ofparamount importance.

As used in detergent compositions, the compounds of the instantinvention are preferably formulated with other components, i.e. builderssuch as sodium tripolyphosphate, anti-redeposition agents such ascarboxymethyl cellulose, brightening agents and the like, in amountsbetween about 10% to 50% by weight of the detergent composition.

The esters of cyclic aminomethyl phosphonic acids were found not only tobe completely miscible with water but also highly soluble in organicsolvents, such as hydrocarbon solvent, i.e. hexane and pentane, carbontetrachloride, haloethylene solvents, i.e., perchloroethylene, ethers,alcohols, and the like. Also, the esters were found to impart asolubilizing action to water in water-immiscible solvents, such as manyof the previously mentioned solvents. This totally unexpected propertyrenders them highly useful as gasoline de-ice additives and along withtheir surfactancy properties render them useful as dry cleaningdetergents. As can be appreciated, however, the unique ability to imparta solubilizing action to Water in water-immiscible solvents can beutilized in many and varied applications and therefore the esters ofcyclic aminomethyl phosphonates are preferred in applications which usethe combined surfactanoy and/or Water solubilizing properties.

The following examples are presented to illustrate the use of the cyclicphosphonates prescribed herein and are presented for purposes ofillustration and not of limitation.

The following test was used to evaluate these compositions as scaleinhibitors.

Procedure Put 50 ml. bicarbonate solution into ml. milk dilution bottle.Add inhibitor (for 100 ml..final volume). Then add 50 ml. CaCl solutionand set in bath at F. Do not cap. Always prepare a blank. Run a hardnessdetermination on a 50-50 mixture before heating.

Heat at 180 F. Take 10 ml. samples from bottles after 2 hours and 4hours.

Filter through millipore filter. Run total hardness on filtrate.Calculate as percent Ca still in solution, i.e.,

Total hardness after heating Total hardness before heating X 100=Percent13 All of the compounds were tested at 180 F.: at 5, 20, and 50 p.p.m.levels. Hardness readings were taken after 2 and 4 hours.

SCALE INHIBITORS The above tests illustrate the superiority of thecyclic phosphonic acids over the aliphatic phosphonic acids (Ex. 7).

USE AS CORROSION INHIBITORS This phase of this invention relates to theuse of these compounds in inhibiting the corrosion of metals, mostparticularly iron, steel and ferrous alloys. These compounds can be usedin a wide variety of applications and systems where iron, steel andferrous alloys are affected by corrosion. They may be employed forinhibiting corrosion in processes which require a protective orpassivating coating as by dissolution in the medium which comes incontact with the metal. They can be used in preventing atmosphericcorrosion, underwater corrosion, corrosion in steam and hot watersystems, corrosion in chemical industries, underground corrosion, etc.

The corrosion inhibitors contemplated herein find special utility in theprevention of corrosion of pipe or equipment which is on contact with acorrosive oil-containing medium, as, for example, in oil wells producingcorrosive oil or oil-brine mixtures, in refineries, and the like. Theseinhibitors may, however, be used in other systems or applications. Theyappear to possess properties which impart to metals resistance to attackby a variety of corrosive agents, such as brines, weak inorganic acids,organic acids, CO H 8, air or oxygen, etc.

The method of carrying out this process is relatively simple inprinciple. The corrosion preventive reagent is dissolved in the liquidcorrosive medium in small amounts and is thus kept in contact with themetal surface to be protected. Alternatively, the corrosion inhibitormay be applied first to the metal surface, either as is, or as asolution in some carrier liquid or paste. Continuous application, as inthe corrosive solution, is the preferred method, however.

The present process finds particular utility in the protection of metalequipment of oil and gas wells, especially those containing or producingan acidic constituent such as H 8, CO air or oxygen, organic acids andthe like. For the protection of such wells, the reagent, eitherundiluted or dissolved in a suitable solvent, is fed down the annulus ofthe well between the casing and producing tubing where it becomescommingled with the fluid in the well and is pumped or flowed from thewell with these fluids, thus contacting the inner wall of the casing,the outer and inner wall of tubing, and the inner surface of allWellhead fittings, connections and flow lines handling the corrosivefluid.

Where the inhibitor composition is a liquid, it is conventionally fedinto the Well annulus by means of a motor driven chemical injector pump,or it may be dumped periodically (e.g., once every day or two) into theannulus by means of a so-called boll weevil device or similararrangement. Where the inhibitor is a solid, it may be dropped into thewell as a solid lump or stock, it may be blown in as a powder with gas,or it may be washed in with a small stream of the well. fluids or otherliquid. Where there is gas pressure on the casing, it is necessary ofcourse, to employ any of these treating methods through a pressureequalizing chamber equipped to allow introduction of reagent into thechamber, equalization of pressure between chamber and casing, and travelof reagent from chamber to well casing.

Occasionally, oil and gas wells are completed in such a manner thatthere is no opening between the annulus and the bottom of the tubing orpump. This results, for example, when the tubing is surrounded at somepoint by a packing held by the casing or earth formation below thecasing. In such wells the reagent may be introduced into the tubingthrough a pressure equalizing vessel, after stopping the flow of fluids.After being so treated, the well should be left closed in for a periodof time sufiicient to permit the reagent to drop to the bottom of thewell.

For injection into the well annulus, the corrosion inhibitor is usuallyemployed as a solution in a suitable solvent. The selection of solventwill depend much upon the specific reagent being used and its solubilitycharacteristics.

For treating Wells With packed-oif tubing, the use of solid sticks orplugs of inhibitor is especially convenient. These may be prepared byblending the inhibitor with a mineral wax, asphalt or resin in aproportion sufficient to give a moderately hard and high-melting solidwhich can be handled and fed into the well conveniently.

The protective action of the herein described reagents appears to bemaintained for an appreciable time after treatment ceases, buteventually is lost unless another application is made.

For example, for the protection of gas wells and gascondensate wells,the amount of corrosion inhibitor used might range between about A to 3lbs. per million cubic feet of gas produced, depending upon the amountsand composition or" corrosive agents in the gas and the amount of liquidhydrocarbon and water produced. However, in no case does the amount ofinhibitor required appear to be stoichiometrically related to the amountof acids produced by a well, since protection is obtained with much lesscorrosion inhibitor than usually would be required for neutralization ofthe acids produced.

These compounds are particularly effective in the prevention ofcorrosion in systems containing a corrosive aqueous medium, and mostparticularly in system containing brines.

These reagents can also be used in the prevention of corrosion in thesecondary recovery of petroleum by water flooding and in the disposal ofwaste water and brine from oil and gas wells. Still more particularly,they can be used in a process of preventing corrosion in water floodingand in the disposal of waste water and brine from oil and gas wellswhich is characterized by injecting into an underground formation anaqueous solution containing minor amounts of the compositions of thisinvention, in sufiicient amounts to prevent the corrosion of metalsemployed in such operation.

When an oil well ceases to flow by the natural pressure in the formationand/or substantial quantities of oil can no longer be obtained by theusual pumping methods, various processes are sometimes used for thetreatment of the oil-bearing formation in order to increase the flow ofoil. These processes are usually described as secondary recoveryprocesses. One such process which is used quite frequently is the waterflooding process wherein water is pumped under pressure into What: iscalled an injection well and oil, along with quantities of water, thathave been displaced from the formation, are pumped out of an adjacentwell usually referred to as a producing well. The oil which is pumpedfrom the producing well is then separated from the water that has beenpumped from the producing well and the water is pumped to a storagereservoir from which it can again be pumped into the injection Well.Supplementary water from other sources may also be used in conjunctionwith the produced water. When the storage reservoir is open to theatmosphere and the oil is subject to aeration this type of waterflooding system is referred to herein as an open water flooding system.If the water is recirculated in a closed system Without substantialaeration, the secondary recovery method is referred to herein as aclosed water flooding systern.

Because of the corrosive nature of oil field brines, to economicallyproduce oil by water flooding, it is necessary to prevent or reducecorrosion since corrosion increases the cost thereof by making itnecessary to repair and replace such equipment at frequent intervals.

I have discovered a method of preventing corrosion in systems containinga corrosive aqueous media, and most particularly in systems containingbrines, which is characterized by employing the compounds describedherein. For example, I have discovered an improved process of protectingfrom corrosion metallic equipment employed in secondary oil recovery byWater flooding such as injection wells, transmission lines, filters,meters, storage tanks, and other metallic implements employed thereinand particularly those containing iron, steel, and ferrous alloys, suchprocess being characterized by employing in water flood operation anaqueous solution of the compositions of this invention.

The invention, then, is particularly concerned with preventing corrosionin a water flooding process characterized by the flooding medium,containing an aqueous or an oil field brine solution of these reagents.

In many oil fields large volumes of water are produced and must bedisposed of where water flooding operations are not in use or wherewater flooding operations cannot handle the amount of produced water.Most States have laws restricting pollution of streams and land withproduced waters, and oil producers must then find some method ofdisposing of the waste produced salt water. In many instances therefore,the salt Water is disposed of by injecting the water into permeable lowpressure strata below the fresh water level. The formation into whichthe water is injected is not the oil producing formation and this typeof disposal is defined as salt water disposal or waste water disposal.The problems of corrosion of equipment are analogous to thoseencountered in the secondary recovery operation by water flooding.

The compounds of this invention can also be used in such water disposalwells thus providing a simple and economical method of solving thecorrosion problems encountered in disposing of unwanted water.

Water flood and waste disposal operations are too well known to requirefurther elaboration. In essence, the flooding operation is effected inthe conventional manner except that the flooding medium contains a minoramount of these compounds, suflicient to prevent corrosron.

While the flooding medium employed in accordance with the presentinvention contains water or oil field brine and the compounds of thisinvention, the medium may also contain other materials. For example, theflooding medium may also contain other agents such as surface activeagents or detergents which aid in wetting throughout the system and alsopromote the desorption of residual oil from the formation, sequesteringagents which prevent the deposition of calcium and/or mag nesiumcompounds in the interstices of the formation, bactericides whichprevent the formation from becoming plugged through bacterial growth,tracers, etc. Similarly, they may be employed in conjunction with any ofthe operating techniques commonly employed in water flooding and waterdisposal processes, for example five spot flooding, peripheral flooding,etc. and in conjunction with other secondary recovery methods.

The concentration of the corrosion inhibitors of this invention willvary widely depending on the particular compound, the particular system,etc. Concentrations of at least about p.p.m., such as about to 7,500p.p.m. for example about 1 to 5,000 p.p.m., advantageously about 10 to1,000 p.p.m., but preferably about 15-250 p.p.m. may be employed. Largeramounts can also be employed such as 1.55.0% although there is generallyno commercial advantage in so doing.

For example, since the success of a water flooding operation manifestlydepends upon its total cost being less than the value of the additionaloil recovered from the oil reservoir, it is quite important to use aslittle as possible of these compounds consistent with optimum corrosioninhibition. Since these compounds are themselves inexpensive and areused in low concentrations, they enhance the success of a floodoperation by lowering the cost thereof.

By varying the constituents of the composition, the compounds of thisinvention can be made more oil or more water soluble, depending onwhether the composition is to be employed in oil or water systems.

Although the manner of practicing the present invention is clear fromthe foregoing description, the following non-limiting specific examplesare included for purposes of illustration.

CORROSION TESTS The test procedure includes measurement of the corrosiveaction of the fluids inhibited by the compositions herein described uponsand-blasted SAE-1020 steel coupons under conditions approximating thosefound in an actual producing well, and the comparison thereof withresults obtained by subjecting identical test coupons to the corrosiveaction of the identical fluids containing no inhibitor.

In the present tests clean pint bottles are charged With 440 ml. of asynthetic brine, which contains 42 g. of sodium chloride, 14 g. calciumchloride, 1 g. of sodium sulfate and 17 g. of magnesium chloride perliter, saturated with hydrogen-sulfide or air and a predetermined amountof inhibitor is then added. The inhibitor concentration is based on thetotal volume of fluid. Bottle caps holding three coupons are then placedtightly on the bottles. The bottles are then placed on a wheel containedin an oven and rotated for 4 hours at -95 F. Corrosion rates are thenmeasured using the three coupons in each bottle as electrodes inconjunction with an instrument for measurement of instantaneouscorrosion rates of the type shown in Ser. No. 332,399 filed Dec. 23,1963. Percent protection is calculated from where R is corrosion rate ofuninhibited fluids R is corrosion rate of inhibited fluids When theinhibitor was oil-soluble as contrasted to water-soluble, a two-phasesystem was used instead of the all-brine system and this simplyconsisted of using hydrogen sulfide saturated mineral spirits to replace25% by volume of the brine.

The following examples are presented to illustrate the use of cyclicphosphonates described herein and are presented for purposes ofillustration and not of limitation.

CORROSION INHIBITOR TESTS TABLE B In H28 saturated brine 02 Protection(p.p.m.)

Composition:

Example 1 78% (50) 78% (100) Example 3 85% (5 (100) Example 63% (100)67% (200) In a saturated brine containing Protection (p.p.m.)

Example 8 78% Example 10 78% (100) It is well known that most corrosioninhibitors of the film-forming or non-reducing type are not tooeffective in preventing corrosion in aerobic systems, i.e. containingair and/or oxygen. However, the compounds of this invention areparticularly suitable for preventing corrosion in aerobic systems. Forexample, they are particularly suitable for systems containing oxygensuch as found in open secondary recovery systems, cooling towers, andthe like.

The composition of this invention can also be employed in conjunctionwith other corrosion inhibitors, for example of the film-forming type.Non-limiting examples include the acylated polyamines such as describedin US. Pats. Re. 23,227, 2,466,517, 2,468,163, 2,598,213 and 2,640,029.These acylated polyamines may be described as amides, imidazolines,tetrahydropyrimidines, etc.

WATER CLARIFICATION This phase of the present invention relates to amethod for the clarification of water containing suspended matter.

Accordingly clarification of water containing suspended particles ofmatter is effected by adding to such water compounds of this invention.

Water containing suspended particles which may be treated by the presentinvention may have its origin either in natural or artificial sources,including industrial and sanitary sources. Waters containing suspendedparticles of natural origin are usually surface waters, wherein theparticles are suspended soil particles (silt), although subsurfacewaters may also be treated according to the present invention. Waterhaving its origin in industrial process (including sanitary water)operations may contain many different varieties of suspended particles.These particles are generally the result of the particular industrial orsanitary operation concerned. Prior to discharging such industrial wastewaters into natural water courses it generally is desired that thesuspended matter be removed.

The present process may likewise be applied to Water contained in stockor fish ponds, lakes or other natural or artificial bodies of watercontaining suspended solids. It may be applied to industrial watersupplied either in preparation therefor, during or after use and priorto disposal. It may be applied to sanitary water supplies either for theelimination of suspended solids prior to use for such purposes, or itmay be applied to such waters which have become contaminated withimpurities from any source.

Most naturally occurring waters contain an amount of simple electrolytes(sodium, potassium, ammonium, calcium, aluminum salts, etc.) in excessof that necessary for the initial aggregation of the ultimate siltparticles. This is likewise true of particles of suspended material inindustrial or sanitary waters. The ultimate particles of silt or othermaterials are therefore naturally somewhat aggregated by reason of thepresence of such electrolytes. However, the forces binding such ultimateparticles together are not great and moreover are not such as togenerally effect either rapid settling rates of the flocculated materialor strong enough to prevent deflocculation.

The compounds of this invention cause rapid flocculation and alsoreinforce the formed aggregates of particles causing a generaltightening or bonding together of the initial particles and an increasedrate of coagulation and settling, thus forming, a less turbidsupernatant liquid.

The addition of the compounds of this invention to the Water suspensionshould be made in such a fashion that the resulting flocculation andaggregation of the particles takes place uniformly throughout. the bodyof water. In order to obtain a uniform addition of the compositions ofthe invention to the water-borne suspension it is generally desirable toprepare a relatively dilute stock solution of the compositions and thento add such solution to the body of water in the proportions indicated.Clarification may take place either in the natural body of water or itmay be caused to take place in hydraulic thickeners of known design.

The amount of the compositions to be employed will vary depending uponthe amount and the degree of subdivision of the solids to beagglomerated or fiocculated, the chemical nature of such solid. and theparticular inventive compositions employed. In general, I employ atleast a sufficient amount of the compositions to promote flocculation.In general, I employ 0.005l0,000 p.p.m. or more such as about 0.S l,000p.p.m., for example about 1500 p.p.m., but preferably about 2-5 p.p.m.Since the economics of these processes are important, no more than theminimum amount required for efficient removal is generally employed. Itis desired, of course, to employ sufficient compostions so flocculationwill take place without causing the formation of stable dispersions.

The precipitating action of the compositions can be employed in theapplication of loading or filling materials to textiles or paper.

In the processing of fine mineral particles in aqueous suspension thefiocculating agents will be especially useful. In the processing of oresto separate valuable mineral constituents from undesirable matrixconstituents, it is frequent practice to grind the one into afinely-divided state to facilitate separation steps such as selectiveflotation and the like. In many ore dressing procedures, thefinely-divided ore is suspended in water to form a pulp or slime. Afterprocessing, it is usually desirable to dewater the pulps or slimeseither by sedimentation or filtering. In such operations, certain oresare particularly troublesome in that the finely-divided ore, whensuspended in water, forms a stable slime which settles very slowly, ifat all. Such slimes are unsuitable for concentration or dewatering bysedimentation and are difiicult to dewater by filtration because of thetendency to clog the pores of the filter, thus leading to excessivelytime-consuming and ineflicient operation of the filters. In some cases,for example, in certain phosphate mining operations, the formation ofvery stable suspensions of finely-divided mineral results not only inthe loss of considerable valuable mineral as waste but also requireslarge expenditures for the maintenance of holding ponds for the waste.Similar problems are involved in processing gold, copper, nickel, lead,zinc, iron, such as taconite ores, uranium and other ores, and theinventive flocculating agents will be useful in these operations.

Some specific additional applications for the compositions of thisinvention, not intended to be limiting but merely illustrative arelisted below. The compositions can be used for the clarification ofbeers or wines during manufacture. Another use is in processingeflluents in pharmaceutical operations for the recovery of valuableproducts or removal of undesirable by-products. A particularly importantuse for these fiocc'ulating agents is in the clarification of both beetsugar and cane sugar juices in their processing. Still another use isfor flocculation and recovery of pigments from aqueous suspensionsthereof. The compositions will be particularly useful in sewagetreatment operations as a flocculating agent. A further use is topromote by flocculation the removal of coal from aqueous suspensionsthereof. In other words, the fiocculating agents of the invention aregenerally useful for processing aqueous efiiuents of all types tofacilitate the removal of suspended solids.

A water soluble or water dispersible compound, to the extent ofeffective concentration, is employed.

These compositions can also be employed in the process of flocculatingwhite water and/or recycling of the precipitate solids in the papermaking process described in US. application S.N. 347,023, filed Feb. 24,1964, and other processes described therein.

Although the manner of practicing the present invention is clear fromthe foregoing description, the following non-limiting specific examplesare included for purposes of illustration.

Naturally occurring water from many sources, and in some instances,brine and brackish waters are used in the recovery of petroleum bysecondary water-flooding operations. Clarification of the water isnecessary in many instances prior to water flooding because thesuspended impurities tend to plug the underground formations into whichwaters are pumped.

EXAMPLES A suspension of FeS in brine was subjected to the action of thewater-soluble compounds prepared herein.

In these tests, the FeS concentration is 25 parts per million and 1% and5% brine solution were used. Metered quantities (500 ml.) of thehomogeneous suspension were placed into 1000 ml. beakers and stirred at10 rpm. The compound to be tested was injected into the suspension togive final active concentrations varying between 2 through 4 parts permillion. Stirring was achieved by use of a Phipp and Bird flocmulti-stirrer. After one minute the stirring rate was reduced to 20 to 30 rpm. and maintained thus for ten minutes. At this time the stirringwas stopped. The evaluation of the compound started at the moment offlocculation and continued with respect to the floc size and rate ofprecipitation. The final evaluation was achieved by visual examinationof the color of the resultant aqueous phase.

The compositions described herein such as those prepared in the specificexamples are employed as flocculating agent.

These compounds are also effective in flocculating the other systemsdescribed herein.

The following is a partial list of industrial systems in which thecompounds of the present invention can be employed as flocculatingagents.

( 1) Petroleum industry (2) Food industry such as in the dairy industry,the canning, freezing and dehydration industries (3) Metal platingindustry (4) Chemical and pharmaceutical industries (5) Mining industry,for example, in the phosphate mining industry such as in phosphateslirnes (6) Fermentation industries, such as in alcohol, beer,

yeast, antibiotics, etc. production (7) Tanning industry (8) Meatpacking and slaughterhouse industry (9) Textile industry (10) Sugarrefining industry (11) Coal industry (12) Soap industry (13) Sewagepurification (14) Corn starch industry (15) Fat processing and soapindustry (16) Paper industry (17) Hydroelectric plants, atomic energyoperations,

boiler plants, etc.

EXAMPLES The compositions described herein, such as those prepared inthe specific examples, are efiective flocculants.

20 OTHER DERIVATIVES These products may be further reacted to formderivatives thereof, for example, they may be oxyalkylated with alkyleneoxides such as ethylene oxide, propylene oxide, butylene oxide, octyleneoxide, alone or in combination; with styrene oxide, glycide, methylglycide, allyl glycidyl ether, glycidyl isopropyl ether, glycidylphenylether, diepoxides, polyepoxides, etc.

They may be reacted with alkylene imines such as ethyleneimine,propylene imine, etc., dialkylaminoepoxypropane of the structureCH2CHCH2NR' where the Rs are alkyl, etc.

OTHER USES In addition to the uses described above, these compositionsand/or derivatives thereof, can be used as follows:

(1) as demulsifiers for water-in-oil and oil-in-water emulsions (2) asbiocides i.e. bacteriocides, algicides, etc.

(3) as additives to various petroleum fuels including gasoline, dieselfuel, jet fuels, etc.

(4) as gasoline anti-icers and anti-stallers (5) as flotation agents,such as flotation collection agents (6) as emulsifiers, for example, inmetal cleaners, auto polishes, wax emulsions, etc.

(7) as additives for sludging oil and cutting oils (8) as fuel dehazingagents (9) as agents for preparing emulsions for the hydrofrac processof enhancing oil recovery (10) as agents to prepare polymer emulsions(11) as agents for the textile industry such as mercerizing assistants,wetting agents, rewetting agents, penetrating agents, dispersing agents,softening agents, dyeing assistants, etc.

( 12) as anti-static agents for textiles, plastics, etc.

(13) as agents in leather processing 14) as lube oil additives (15) asemulsifiers for insecticidal and agricultural compositions 16) asadditives for primer paints to help insure adhesion to metallic surfacesand give corrosion protection (17) as additives useful as a freeze-thawstabilizer for latex-base paints (1-8) as agents for the pulp and paperindustry, such as sizing aids, etc.

(19) as general metal deactivators 2. The process of claim 1 where thenitrogen-heterocyclic phosphonic acid has the following formula:

where 21 represents said nitrogen-heterocyclic ring, R' NH represents anamino terminated side chain attached directly to the ring nitrogen,where x is zero or 1, y is 1 or 2 and z is zero or 1 with the provisosthat (1) y is 1 when z is zero and (2) x is 1 andy is 1 when z is 1 and(3) x is zero when y is 2 and z is 1, and

represents the methyl, or substituted methyl, phosphonic acid where M ishydrogen, an alcohol or a salt moiety, and X and Y are hydrogen, alkylor aryl.

3. The process of claim 2 where Q represents morpholine.

4. The process of claim 3 wherein the inhibitor is a member of the groupconsisting of 5. The process of claim 2 where 6 represents piperazine.

6. The process of claim wherein the inhibitor is a member of the groupconsisting of (2) a mixture of and and (4) a mixture of ll (HOMHCHz-NN-CHZCHZNHCH2P (OH);;

and

0 (Emai CHz-N N-CHzCHzOH 22 7. The process of claim 6 wherein theinhibitor is a mixture of II II (HO)2PCHzN N-CHzCHgNHCHzP (OH):

and

rrmzis oni-ri N 41110112011 8. The process of claim 2 where U representsimidazoline.

9. The process of claim 8 wherein the inhibitor has the formula where Ris a hydrocarbon group.

10. The process of claim 9 where R is C7H15 and M is hydrogen.

11. The process of claim 8 wherein the inhibitor has the formula n NNCHzCHzNHCH2P(OH)z where R is a hydrocarbon group.

12. The process of claim 11 where R is C17H35.

13. The process of claim 8 wherein the inhibitor has the formula where Ris a hydrocarbon group.

14. The process of claim 13 where R is C H References Cited

